In this thesis, design and implementation of a distribution-type, voltage source converter (VSC) based static synchronous compensator (D-STATCOM) having the simplest converter and coupling transformer topologies have been carried out. The VSC STATCOM is composed of a +/- 750 kVAr full-bridge VSC employing selective harmonic elimination technique, a low-pass input filter, and a &amp / #8710 / /Y connected coupling transformer for connection to medium voltage bus. The power stage of VSC based STATCOM is composed of water-cooled high voltage IGBT modules switched at 850 Hz for the elimination of 5th, 7th, 11th, 13th, 17th, 19th, 23rd,and 25th voltage harmonics. Special care has been taken in the laminated busbar design to minimize stray inductances between power semiconductors and dc link capacitor. Reactive power control is achieved by applying the phase angle control technique. The effect of input filter on total demand distortion has been investigated theoretically by mathematical derivations. The proposed VSC STATCOM has been implemented for reactive power compensation of Coal Preparation System in Kemerk&ouml / y Thermal Power Plant. The field test results have shown the success of the implemented system in view of fast response in reactive power compensation, and minimum input current harmonic content, and compliance with the IEEE Std. 519-1992 even for the weakest power systems. The application of selective harmonic elimination technique and phase angle control to VSC STATCOM has led to optimum switching frequency and device utilization for high voltage IGBTs at the expense of slower response as compared to other PWM techniques.

With the deregulation of power industry and the market competition, reliable power supply and secured system operation are major concerns of the independent system operator (ISO) or decision-maker (DM). Power dispatch under deregulated environment is complicated with various possibilities of decisions involved. Without the assistance of Energy Management System (EMS), it is not easy for ISO or DM to operate with pure experiences. To enhance the operational efficiency, EMS involves the state-of-the-art control technology, and the fast and effective computer assisted decision support system will help dispatch the power. A conventional EMS has a few major tasks, among them, the ¡§network analysis¡¨ task and the ¡§forecast and scheduling¡¨ task are the most important in assisting the on-line power dispatch. In dealing with the new deregulated environment, an ¡§operational planning¡¨ has to be added to aid the EMS for more security. There are significant changes on EMS after deregulation. This dissertation will focus on the changes and new functions, in the ¡§network analysis¡¨ and the ¡§forecast and scheduling¡¨ tasks of an EMS, which supports the operation in the competitive environment. In the ¡§network analysis¡¨ task, we discuss the real and reactive power dispatch and congestion management with AC optimal power flow (OPF). In this task, the formulation of AC OPF with deregulation issues and the effect of flexible AC transmission systems (FACTS) devices are presented. A predictor-corrector interior-point nonlinear-programming (PCIPNLP) algorithm has been developed to solve the problem. The model involves only slight modification to the present OPF for social welfare maximization to obtain the optimized bid-based dispatch and nodal spot prices. The incorporation of FACTS devices for system operations can ease the difficulties caused by transmission congestion. It is found that PCIPNLP technique is very effective for the modified OPF solution for congestion relief under deregulation. In the ¡§forecast and scheduling¡¨ task, we discuss the resource scheduling for bid-based dynamic economic dispatch and spot dispatch for power and reserve. They can be formulated for social welfare maximizing problem that is solved by using an efficient interior point method. And the optimal resource allocation and nodal spot price can be given from the various test results. We have also proposed a fuzzy based strategic gaming method to determine the GenCo¡¦s bidding strategy. Based on fuzzy set theory, a multi-criteria decision-making method is used to obtain the optimal strategy combination, bids and expected payoffs. Decision maker can find the optimal strategy combination by using weight vector to represent his subjective attitude about the structure of multi-objectives. The advantages have also been demonstrated through the numerical examples. Compared with the classical (¡§nonfuzzy¡¨) game theory, the proposed approach could help the decision maker to obtain higher expected payoffs, and make his choices easily. Possible applications of the proposed fuzzy method can be suggested for other decision-making problems in the power systems

Η παρούσα διπλωματική ασχολείταιμε τις σύγχρονες μεθόδους που εφαρμόζονται στα συστήματα ηλεκτρικής ενέργειας για την βελτίωση των χαρακτηριστικών τους χρησιμοποιώντας αφενός τις τεχνολογικές εξελίξεις στον τομέα των ημιαγωγικών διακοπτικών στοιχείων και αφετέρου την εγκατεστημένη θεωρία ελέγχου. Στο κεφάλαιο 1 επιχειρείται μια εισαγωγή στις έννοιες των συστημάτων μεταφοράς ηλεκτρικής ενέργειας (ΣΗΕ) καθώς και στην αρχή λειτουργίας τους.Στη συνέχεια γίνεται αναφορά στην έννοια της ποιότητας ισχύος και στα προβλήματα που παρουσιάζονται στα ηλεκτρικά δίκτυα. Τέλος αναφέρονται τα προβλήματα εκείνα που με την πάροδο του χρόνου έκαναν επιτακτική την εισχώρηση της τεχνολογίας των ηλεκτρονικών ισχύος στο πεδίο τους και ιδιαίτερα στην κατεύθυνση της αντιστάθμισης αέργου ισχύοςπου αποτελεί ένα απο τα κυριότερα προβλήματα. Στο κεφάλαιο 2 συνεχίζουμε αναλύοντας τη μορφή που παίρνουν τα σύγχρονα ΣΗΕ μετά την είσοδο της τεχνολογίας των FACTS ξεκινώντας από τα θυρίστορ ,ηλεκτρονικούς διακόπτες ισχύος,που αποτελούν δομικά στοιχεία των νέων διατάξεων και επόμενα τις γενικότερες διατάξεις που χρησιμοποιούνται στα ΣΗΕ που συνδυάζουν τα νέα στοιχεία ακόμα και με τους μηχανικούς διακόπτες που ήταν ο προηγούμενος τρόπος ελέγχου των ΣΗΕ. Στο κεφάλαιο 3 γίνεται μια πιο ενδελεχή αναφορά στα κυκλώματα τεχνολογίας ηλεκτρονικών ισχύος που χρησιμοποιύνται ώστε να πάρουν μορφή οι προηγούμενες διατάξεις ,ξεκινώντας από τη βασική μονάδα του μετατροπέα ημιγέφυρας δομικό στοιχείο των DC/AC μετατροπέων.Ακόμα στο κεφάλαιο αυτό αναφερόμαστε στον έλεγχοτων διατάξεων ,αναλύοντας τα συστήματα αναφοράς και τις τεχνικές που υπάρχουν για να καταστεί δυνατή η οδήγησή τους. Στο κεφάλαιο 4 τα πράγματα γίνονται πιο συγκεκριμένα και αναφερόμαστε στο στατικό αντισταθμιστή (STATCOM).Παρουσιάζονται τα κυκλώματα ελέγχου που περιέχει έτσι ώστε να γίνεται δυνατός ο έλεγχος τάσης είτε διάφορες άλλες δυνατότητες που μπορεί να προσφέρει στο πλαίσιο της καλύτερης λειτουργίας των σύγχρονων ΣΗΕ.Επίσης αναπτύσσεται το μαθηματικό και δυναμικό μοντέλο με τις εξισώσεις στα βήματα του οποίου θα κινηθεί και η προσομοίωση του επόμενου κεφαλαίου. Στο κεφάλαιο 5 γίνεται προσομοίωση της λειτουργίας του στατικού αντισταθμιστή και παρουσιάζονται διάφορα διαγράμματα από τα επιμέρους κυκλώματα που αναδεικνύουν τη λειτουργία του.Κύριο αντικείμενο και εδώ αποτελεί η θεωρία ελέγχου και ιδιαίτερη μνεία γίνεται στην χρησιμοποίηση των PI ελεγκτών εκείνω οι οποίοι ρυθμίζουν παραμέτρους του συστήματος και μετουσιώνουν τη μετάβαση από τα παλαιότερα συστήματα που χρησιμοποιούνταν στα ΣΗΕ όπως ο έλεγχος με μηχανικούς διακόπτες. Στο κεφάλαιο 6 τέλος προχωράμε σε κάποιες ιδέες και προτάσεις για μελλοντική έρευνα ως αποτέλεσμα της ενασχόλησης με την συγκεκριμένη διπλωματική εργασία. / In capter 1 there is an intoduction to the Electrical Power Systems terminology,as well as their function and principles.Next,the meaining of power quality is presented along with the problems that occur at the electrical main grids.More emphsis is given to the ones that gradually enforced the use power electronics for reactive power compensation. In chapter 2,an analysis is made about the form of the modern Electrical Power Systems after the development of the FACT technology,starting from thyristors ,electronic power switches,which are elementsof the new layout and continuing with other modern devices which combine these new elements even with the old mechanical switches. In chapter 3,the electronic power systems' circuits are examined more thorouglyin order to understand the layout of the aforementioned structures,starting from the elementary unit of the half bridge power converter.Moreover,the control of these structures is examined,analyzing the reference systems and the various techniques in order to drive them. Chapter 4, presents the static compensator (STATCOM) along with its control circuits.In addition, the mathematical and dynamic model is developed, forming equations where the simulation of the next chapter is based. In chapter 5,there is a simulation of STATCOM's function (in MATLAB software) and various diagrams are presented showing different variables during its operation.Main purpose of this section is the presentation of the control theory,highlighting the use of PI controllers which adjust the system's parameteres and realize the transition from the older structures used in Electrical Power Systems ,such us mechanical switching. In chapter 6,we present some ideas in terms of future survey as a result of our dealing with the certain thesis

Scientific evidence is increasingly relied on in litigation. Discussions and debates aimed at enabling courts to make the best use scientific evidence are therefore critical. This thesis adds the perspective of procedural legitimacy to the science and law dialogue. Procedural Legitimacy is the concept that consistent adherence to legal procedure maintains the overall legitimacy of the legal system, and the validity of its outcomes. I argue that to maintain legitimate legal outcomes, procedural rules must be applied consistently and vigilantly to scientific evidence. This means that admissibility rules must be applied properly to scientific evidence, and that admitted scientific evidence must be duly scrutinized and weighed against the legal standard of proof. This ensures that the legal outcome will be based on valid legal facts. When the law is applied to those legal facts, litigants are legitimately bound by the judicial decision, despite the risk of factual inaccuracy. / The bulk of this thesis develops the notion of procedural legitimacy, and argues that its role in the adjudicative process is vital. The argument is founded on the conditions of uncertainty in which legal decisions are made. I show that both liability determinations and damages determinations in personal injury actions are made in conditions of uncertainty, and are dependent on consistency in procedure to maintain legitimacy. Ultimately, I apply the procedural legitimacy argument to admissibility and use of scientific evidence, and endorse the recommendations of the Goudge Inquiry in that respect.

The focus of this research is on deriving small signal stability models for different Flexible AC Transmission Systems devices by introducing a simple systematic method that is applicable to any dynamic device. Two different small signal models for Unified Power Flow Controllers are introduced. One model is called the power control mode and the other model is the voltage control mode. The two models are compared from transient stability point of view to show the necessity of developing both models for UPFC. The thesis also shows how to derive the small signal stability model of Static Synchronous Compensator, as the shunt branch of UPFC. The small signal stability models of both devices are then validated to ensure the accuracy of the derived models. STATCOM and UPFC power control mode are validated against PSCAD. The UPFC voltage control mode is validated against nonlinear solution of system equations.

The focus of this research is on deriving small signal stability models for different Flexible AC Transmission Systems devices by introducing a simple systematic method that is applicable to any dynamic device. Two different small signal models for Unified Power Flow Controllers are introduced. One model is called the power control mode and the other model is the voltage control mode. The two models are compared from transient stability point of view to show the necessity of developing both models for UPFC. The thesis also shows how to derive the small signal stability model of Static Synchronous Compensator, as the shunt branch of UPFC. The small signal stability models of both devices are then validated to ensure the accuracy of the derived models. STATCOM and UPFC power control mode are validated against PSCAD. The UPFC voltage control mode is validated against nonlinear solution of system equations.

The object of this research is to optimize the overall power system performance using FACTS devices. Particularly, it is intended to improve the reliability, and the performance of the power system considering steady state operating condition as well as the system subjected to small and large disturbances. The methodology proposed to achieve this goal corresponds to an enhanced particle swarm optimizer (Enhanced-PSO) that is proven in this work to have several advantages, in terms of accuracy and computational effort, as compared with other existing methods. Once the performance of the Enhanced PSO is verified, a multi-stage PSO-based optimization framework is proposed for optimizing the power system reliability (N-1 contingency criterion). The algorithm finds optimal settings for present infrastructure (generator outputs, transformers tap ratios and capacitor banks settings) as well as optimal control references for distributed static series compensators (DSSC) and optimal locations, sizes and control settings for static compensator (STATCOM) units. Finally, a two-stage optimization algorithm is proposed to improve the power system performance in steady state conditions and when small and large perturbations are applied to the system. In this case, the algorithm provides optimal control references for DSSC modules, optimal location and sizes for capacitor banks, and optimal location, sizes and control parameters for STATCOM units (internal and external controllers), so that the loadability and the damping of the system are maximized at minimum cost. Simulation results throughout this research show a significant improvement of the power system reliability and performance after the system is optimized.

[pt] Esta tese visa propor uma delimitação ontológica entre eventos, fatos e estados de coisas, a partir de uma ontologia realista/platonista, e relacionar a ontologia lógica à linguagem em uso, a partir da análise da referência a essas entidades. Eventos, fatos e estados de coisas têm estado presentes na discussão analítica desde os tempos de Frege; no entanto, a discussão ainda continua. Eventos têm sido reduzidos a objetos, a fatos e a estados de coisas; fatos têm sido reduzidos a estados de coisas e a proposições; estados de coisas e fatos têm sido considerados como a mesma entidade, e assim por diante. Essas três entidades estão associadas à linguagem desde os tempos de Russell (1918). Os fatos eram relacionados às afirmações verdadeiras, sendo compreendidos como as entidades às quais apontavam essas afirmações. Os eventos eram relacionados com as sentenças de ação. De acordo com Davidson (1981a), temos sentenças de ação porque há eventos no mundo. Embora esta tese vise relacionar a ontologia à linguagem em uso, ela as desvincula num primeiro momento; por isso define a ontologia independentemente da linguagem. Propõe que a diferença entre eventos, fatos e estados de coisas é que os primeiros são concretos e os últimos, abstratos, entre outras características. Uma vez definida a ontologia, a relacionamos, a partir da referência, com a linguagem em uso. Analisamos se é possível referir a essas entidades a partir da análise de certas construções linguísticas, e vemos se é possível estabelecer tal relação a partir dessa análise. / [en] This thesis proposes an ontological delimitation between events, facts and states of affairs. It does so from a Platonist/realist perspective. It also relates the logic ontology to language use through the analysis of reference to these entities. Events, facts, and states of affairs have been present in the discussion of analytical philosophy from the times of Frege. However, the discussion still continues, and nothing has been defined. Events have been reduced to objects, facts and states of affairs. Facts have been reduced to states of affairs and propositions. States of affairs and facts have been considered as the same entity by some authors, and so forth. These three entities have been associated to language since the times of Russell (1918). Facts were related to true statements, and were understood as entities to which those statements pointed. Events were related to action sentences. According to Davidson (1981a), we have action sentences because there are events in the world. Though this thesis relates ontology to language, it defines ontology independent of language use. That is, ontology is defined without taking language use into account. It proposes that the difference between events, facts, and states of affairs is that the first are concrete, and the last abstract. Among other characteristics. Once we define the ontology, we relate it to language use through reference. We analyze whether it s possible to refer to events, facts, and states of affairs, because we understand that it is through reference that we may establish the relationship between ontology and linguistics.

Le droit du travail a connu au cours de ces trente dernières années des évolutions remarquables avec, d’une part, l’apparition de nouvelles technologies de l’information et de la communication au sein des entreprises et, d’autre part, l’émergence de l’exigence de justification. Alors que les employeurs sont désormais tenus d’énoncer leurs raisons d’agir et que les salariés travaillent sur des postes informatisés, se pose la question de savoir dans quelle mesure ces nouvelles caractéristiques du monde du travail ont modifié les règles de preuve applicables en la matière. Si la charge de la preuve ne paraît pas avoir été affectée par ces différentes évolutions, il en va différemment de l’objet de la preuve. En effet, l’apparition des toutes dernières technologies de l’information et de la communication participe, au-delà des apparences, à un déplacement de l’objet de la preuve, les salariés ayant désormais accès à de nouveaux éléments de preuve susceptibles d’emporter la conviction des juges. Par ailleurs, l’exigence de justification invite les juges à contrôler plus avant la décision des employeurs. Ces derniers doivent en effet désormais expliciter leurs raisons d’agir. Cela signifie concrètement qu’ils ne peuvent se contenter d’invoquer des faits objectifs, ils doivent encore convaincre les juges de la justesse de leurs décisions en détaillant les ressorts de ces dernières. Ainsi, alors que la doctrine classique avait pour habitude d’affirmer que l’offre de preuve attendue des plaideurs porte sur des faits pertinents, contestés et contestables, l’exigence de justification nous amène à ajouter des faits « contextués », c’est-à-dire des faits articulés au sein d’un discours cohérent et si nous avions pu penser dans un premier temps que l’émergence de l’exigence de justification se traduise par une part croissante de subjectivité dans les décisions de justice, force est de reconnaître au contraire que le contrôle des juges s’est renforcé / The labor law knew during these last thirty years remarkable evolutions with the appearance of new information technologies and communication in the companies and, the creation of “justification’s requirement”. In the mean time employers are now obliged to detail the motivations of their actions and the employees are working more and more on informatics work station. It’s important to understand how these new characteristics have modified the application of the rules of the proof. If the proof’s burden seems to not have been affected by these evolutions, it is not the same about the proof’s object. Indeed, beyond the appearances, the new information and communication technologies lead to a modification of the proof object by giving to the employees the access of new elements of proof susceptible to influence the judge’s conviction. Besides, the “justification’s requirement” invites the judges to better control the employer’s decision. They have now the obligation to clarify their reasons for action. Concretely it means that, to support their claims, they can’t just argue objective facts to convince the judge but they have to justify the logic of their decisions. So, while the classic doctrine had for practice to expect relevant, controversial and questionable facts as proof objects, the “justification’s requirement” brings us to add “sensible facts" (facts articulated within a coherent speech). If at the first time, we could think that the “justification’s requirement” emergence will lead to subjective decision, we are obliged to admit the reinforcement of the judge control.

Este trabalho apresenta proposta de modelo matemático para o problema de expansão do sistema de transmissão baseado no fluxo de carga CC considerando a utilização de links CC e FACTS resolvido através de metodologia de solução que considera a primeira e a segunda lei de Kirchhoff em processo enumerativo de branch-and-bound adaptado. A abordagem possui dois pontos em destaque: i) apresenta uma proposta de modelo matemático com possibilidade da utilização direta em problemas de expansão de linhas de transmissão que possuem tanto linhas de transmissão CA, transformadores, links CC e dispositivos FACTS e ii) é um método exato de solução do problema que garante a otimalidade da resposta e traz uma contribuição ao tradicional método branch-and-bound por incluir relaxações adicionais. O método aplicado aos sistemas de 6 barras de Garver e sistema Sul sudeste Brasileiro de 46 barras apresenta respostas adequadas e o modelo matemático testado em um sistema Garver modificado apresenta novas configurações possíveis com redução do custo total do investimento. / This work proposes a mathematical model to the transmission expansion system problem based on the DC power flow model considering the use of DC links and FACTS that is solved using a solution method considering the first and second Kirchhoff’s Law in an enumerative adapted branch-and-bound process. It is possible to highlight two key aspects of the proposed approach: i) presents a mathematical model that can be directly used on expansion transmission systems problems that have AC transmission lines, transformers, DC links and FACTS and ii) is an exact solution method that guarantees the optimum problems’s solutions and contributes to the traditional branch-and-bound method bringing additional relaxations. The solution method applied to Garver’s six-bus network and southeast Brazilian 46 bus network provides correct answers and the mathematical model tested on a modified Garver’s six-bus network presents new possible configurations that enables overall cost reduction to the problem.